Preparation Of Superhydrophilic And Superoleophobic Membrane And The Application In Determination Of Oil Acid Number

Oil/water separation problem is received extensive attention of the international community.Inspired by different interfacial energy of immiscible oil/water mixtures,application of correlative materials with specific wettability would be an effective way to solve this problem.In this paper,tow kinds of anticorrosive membranes with superhydrophilicity and underwater superoleophobicity were prepared and their oil-water separation performance and stability were evaluated.The membrane was successfully used in oil/water separation process of oil acid number?AN?analysis under corrosive environment.Organic-inorganic hybrid membrane was fabricated by one-step solution immersion method.Here,a hydrophilic and oleophobic membrane was prepared by coating chitosan?CTS?and polyvinyl alcohol?PVA?on the surface of copper mesh using glutaraldehyde?GA?as cross-linking agent.After introduction of TiO₂ nanoparticles,the surface roughness of the composite film was increased and a superhydrophilicity/underwater superoleophobicity surface was obtained due to the enhancement in wettability.The effect of CTS,PVA,GA and TiO₂ on the microstructure and underwater oil contact angle were comprehensively evaluated.Then the superhydrophilic membrane was used for oil/water separation,a separation efficiency?>99.7%?was obtained and the intrusion pressures for all tested oils that the membrane can support are above 1.0 kPa.After repeated use for 60 times,the separating performances and average permeate fluxes showed no obvious degradation.Significantly,compared with the prepared organic-inorganic hybrid membrane,the superhydrophilic membrane exhibited better stability and anti-corrosive property.Therefore,the organic-inorganic hybrid membrane can be used in oil/water separation under corrosive environment.However,the preparation process of organic polymer membrane material is relatively complex and the membrane is easy to swell in the aqueous solution,which limits its application in the actual environment.Therefore,the fabrication of oil-water separating membrane by using inorganic materials has become a good choice.Based on electrodeposition of Zn/ZnO crystal on copper mesh,a highly efficient oil-water separation device was fabricated through a facile one-step method.The electrodeposition process was optimized by varying the applied voltage and duration.The novel all-inorganic membrane exhibited superhydrophilicity in air and underwater low-adhesive superoleophobicity.The separation efficiencies of all tested oil/water mixtures are more than 99.5%and the intrusion pressures for all tested oils that the mesh can support are above 1.5 kPa.The separation performances of the mesh showed no obvious variation after being reused for 60 times,demonstrating its excellent reusability and stability.More importantly,the mesh can be applicable for corrosive solutions including acid,alkali and brine.The good durability and the anti-corrosive property allowed the separation device to be employed in oil/water separation process of oil AN analysis under alkaline environment.The all-inorganic superhydrophilic-underwater superoleophobic membrane was successfully used in oil/water separation process of oil AN analysis.The oil/water mixed,separation and sample analysis block was design through three-dimensional printing,and combined flow injection analysis technology with ion selective electrode to integrate the industrial equipment for an automatic oil acid number detector.The parameter of the flow rate of mixing streams and FIA system were optimized to achieve the online monitoring of the oil AN.The oil AN could be accurately determined with a limit of detection of 0.1 mg KOH/g and the results were consistent with those obtained from the standard method.The analysis specially do not need organic reagent,and the testing frequency is high with a speed of 12/h.